Inside Dropbox: Understanding Personal Cloud Storage Services

Personal cloud storage services are gaining popularity. With a rush of providers to enter the market and an increasing of- fer of cheap storage space, it is to be expected that cloud storage will soon generate a high amount of Internet traffic. Very little is known about the architecture and the perfor- mance of such systems, and the workload they have to face. This understanding is essential for designing efficient cloud storage systems and predicting their impact on the network. This paper presents a characterization of Dropbox, the leading solution in personal cloud storage in our datasets. By means of passive measurements, we analyze data from four vantage points in Europe, collected during 42 consecu- tive days. Our contributions are threefold: Firstly, we are the first to study Dropbox, which we show to be the most widely-used cloud storage system, already accounting for a volume equivalent to around one third of the YouTube traffic at campus networks on some days. Secondly, we characterize the workload typical users in different environments gener- ate to the system, highlighting how this reflects on network traffic. Lastly, our results show possible performance bot- tlenecks caused by both the current system architecture and the storage protocol. This is exacerbated for users connected far from control and storage data-center

Data Availability Sampling in Ethereum: Analysis of P2P Networking Requirements

Despite their increasing popularity, blockchains still suffer from severe scalability limitations. Recently, Ethereum proposed a novel approach to block validation based on Data Availability Sampling (DAS), that has the potential to improve its transaction per second rate by more than two orders of magnitude. DAS should also significantly reduce per-transaction validation costs. At the same time, DAS introduces new communication patterns in the Ethereum peer-to-peer (P2P) network. These drastically increase the amount of exchanged data and impose stringent latency objectives. In this paper, we review the new requirements for P2P networking associated with DAS, discuss open challenges, and identify new research directions

Un cambio de percepciones que me han abierto camino a mi libertad y en esto, a reconocer sus libertades

Màster en Estudis de la Diferència Sexual, Universitat de Barcelona. DUODA, Centre de recerca de dones, curs: 2012-2013, Tutora: Remei Arnaus i MorralMi investigación se basa en la igualdad de los sexos, y en cómo esta se ha confundido con la Equidad de Género, la que sin duda ha sido promocionada por los gobiernos que hoy imperan, a mi modo de ver, como forma de someternos a un neutralismo intenso donde nuestro único foco de reconocimiento sea lo masculino, lo impuesto y lo dado. Sin embargo, en este trabajo intento recoger la mirada de muchas mujeres provenientes de sectores vulnerables y empobrecidos con la idea de entender desde ellas el significado de esta igualdad, si la reconocen, si la viven, si la quieren… En este trabajo, he querido dejar fuera a las grandes teorías de ilustres autores y enfocarme en la respuesta y en la vivencia de ellas mismas, de su lucha diaria y desde aquí crear una nueva teoría, nuestra teoría

The potential of a novel antiangiogenic VEGFR1-D2 binding peptide in oncology therapeutics

Background Tumor growth depends on pro-angiogenic vascular endothelial growth factors (VEGF-A/-B) via binding to VEGF receptors (VEGFR1 and VEGFR2) that are biomarkers of tumor angiogenesis. Importantly, interfering with this interaction by small molecules impairs tumor growth and angiogenesis. Methods A novel peptide (known as VGB3) was synthesized using a solid-phase peptide synthesis (SPPS) procedure on 2-chlorotrityl chloride (2-CTC) resin. A disulfide bridge was formed in the peptide and it was purified using RP-HPLC. Recombinant His-tagged VEGFR1D2 obtained from inclusion bodies and purified on a Ni2+-NTA agarose resin. The equilibrium constant for the binding of VGB3 to VEGFR1-D2 molecule was determined by microscale thermophoresis (MST). The accumulation of the peptide in 4T1 mammary carcinoma tumors (MCTs) was assessed using 2D optical imaging. Anti-angiogenic activity of VGB3 were investigated using MTT, scratch assay, and two- as well as three-dimensional angiogenesis assays. Downstream signaling pathways were assessed by quantitative estimation of protein expression using western blotting and immunohistochemistry. (IHC). Results We have indicated that VGB3 is able to block VEGFR1-D2 in human umbilical vein endothelial cells (HUVECs) and 4T1 mammary carcinoma tumor (MCT) cells. This resulted in inhibition in proliferation of HUVEC, 4T1 MCT, and U87 glioblastoma cells and MST results reveals that VGB3 is a high-affinity (Kd=1.96± 0.69 µM, n = 3, P < 0.0001) binder to VEGFR1-D2. Moreover, fluorescence imaging in Balb/c mice demonstrated that fluorescein isothiocyanate (FITC)-VGB3 accumulated in tumors. VEGFA-stimulated proliferation, migration, and 2 and 3D tube formation in HUVECs were strongly inhibited by VGB3 (n = 3, P < 0.0001). In a murine 4T1 MCT model, VGB3 strongly inhibited AKT and ERK1/2 phosphorylation and tumor cell downstream signaling pathways associated with proliferation, migration, and angiogenesis, and led to the increased apoptosis index and suppression of systematic spreading of the tumor compared to PBS-treated controls. Conclusions These results indicate that VGB3 may be applicable for antiangiogenic and antitumor therapy

EFFECT OF FAVA BEAN EXTRACTS ON THE ERYTHROCYTE POTASSIUM TO HEMOGLOBIN RATION IN NORMAL SUBJECTS AND G6PD DEFICEICY PATIENTS

A procedure for the in vitro evaluation of the toxicity of fava beans has been applied to 17 varieties of the bean and one batch of beans purchased on the open market; the latter consisted of unknown varieties. The procedure involves the incubation of a saline extract of the beans with red cells from normal individuals and with red cells from G6PD deficient patients. 2. Normal red cells under those circumstances absorb potassium from the fava bean extract whereas the cells from G6PD deficient patients lose potassium. 3. This work suggest a relation between the toxicity of the fava beans and the lose of potassium by the red cells. On the basis of this assay, it appears that two of the 17 varieties may be non-toxic

Low-frequency noise in quasi-ballistic monolithic Al–Ge–Al nanowire field effect transistors

International audienceIn this work, Al2O3-passivated, monolithic, and crystalline Al–Ge–Al heterostructure nanowire field effect transistors (FETs) with Ge channel lengths ranging from 18 to 826 nm are analyzed from a low-frequency noise perspective. 1/f and random telegraph noise (RTN) are analyzed in an accumulation mode, where the hole channel is formed by applying a back-gate potential VG. The normalized power spectral density of drain current fluctuations of 1/f noise (SID/ID2) at medium currents follows nearly an 1/ID trend. 1/f noise is analyzed within both the mobility and carrier number fluctuation models (MFM and CNFM), respectively. Taking the MFM into account, the Hooge noise parameter α spreads in the interval of 1.5 × 10−4 to 4 × 10−2, with lower values for shorter devices. Using the same data and the CNFM, the density of interface states Dit in the Al2O3/GexOy/Ge system was estimated using the transconductance extracted from the quasi-static transfer I/V characteristics. The extracted Dit values range from 5 × 109 to 3 × 1012 cm−2 eV−1. Contact noise has also been observed in some devices at high currents. RTN analyzed in time domain exhibits a relative RTN amplitude in the 0.3%–20% range. Capture and emission time constants as a function of VG exhibit a typical behavior for metal oxide semiconductor FETs. The extracted noise parameters are comparable with Ge and III–V nanodevices of top-down and bottom-up technologies